Deep Anterior Lamellar Keratoplasty Using Big-Bubble Technique for Treatment of Corneal Stromal Scars

Incidence and Clinical Features of Immunologic Rejection After Deep Anterior Lamellar Keratoplasty

PURPOSE

The aim of this study was to investigate the incidence and clinical features of immunologic rejection after deep anterior lamellar keratoplasty (DALK).

METHODS

This study included 411 patients (464 eyes, median age [interquartile range; IQR] 55.8 years [36.1-69.5]) who underwent DALK at Tokyo Dental College between June 1997 and 2021. Of 411 patients, 24 (24 eyes [5.2%], 51.9 years [IQR 31.6-65.4]) developed immunologic rejection. We characterized the clinical features, risk factors associated with immunologic rejection, and prognosis.

RESULTS

The interval between DALK and immunologic rejection was 14.5 (range, 5-78) months. Immunologic rejection occurred after cessation/reduction of topical steroid in 9 (47.4%) and suture removal in 4 eyes (21.1%). The postoperative duration of topical steroid use in eyes with immunologic rejection was significantly shorter (10.0 months, [IQR 6.0-14.0]) than those without immunologic rejection (28.3 [IQR 15.8-42.7], P = 0.001). Immunologic rejection manifested as stromal edema in 19 (100.0%), ciliary hyperemia in 17 (89.5%), keratic precipitates in 13 (68.4%), epithelial edema in 13 (68.4%), infiltration in 9 (47.4%), corneal opacity in 4 (21.1%), and Descemet membrane detachment in 2 eyes (10.5%). After treatment, corneal clarity was restored in 17 eyes (89.5%); however, immunologic rejection led to corneal endothelial decompensation in 2 eyes (10.5%). Endothelial cell density decreased from 1795.7 ± 722.6 to 1651.6 ± 655.6 cells/mm 2 after immunologic rejection ( P = 0.074).

CONCLUSIONS

Post-DALK immunologic rejection was associated with specific clinical triggers such as reduction/cessation of topical steroids or suture removal.

Influence of Opacity Depth on Big Bubble Formation During Deep Anterior Lamellar Keratoplasty in Corneal Stromal Scars

PURPOSE

To identify the key preoperative predictors of big bubble (BB) formation during deep anterior lamellar keratoplasty in patients with corneal stromal scars (CSS).

METHODS

This retrospective cohort study included consecutive patients with CSS after infective keratitis who underwent BB-deep anterior lamellar keratoplasty between January 2021 and July 2023 at a tertiary referral center. Topographic and tomographic data were collected to compare the rates and types of BB formations. Anterior segment optical coherence tomography (AS-OCT) was employed to assess the maximum depth of opacity by dividing the stroma into 3 zones of equal thickness: anterior (stage A), mid (stage B), and posterior stroma (stage C). Multivariate logistic regression analysis was performed to identify the potential preoperative predictors of bubble formation.

RESULTS

Pneumatic dissection was achieved in 13 of 33 eyes (39.4%), with 11 BB type 1 eyes (33.3%) and 2 BB type 2 eyes (6.1%). According to AS-OCT grading, bubble formation was more frequent with CSS involving more superficial stromal layers (P <0.032). In the eyes with stage C, bubble formation failed 12 out of 14 times (85.7%, P <0.026). Spearman correlation showed that bubble formation was inversely associated with the AS-OCT grading (rho = -0.443, P = 0.001). After logistic regression analysis, AS-OCT grading was found to be the sole factor that predicted bubble formation (coeff. -1.58, confidence interval 95% -3.03 to -0.12, P = 0.034).

CONCLUSIONS

Depth of opacity in CSS was the key determinant for predicting the success of pneumatic dissection, as advanced AS-OCT stages are strongly associated with BB failure.

Management and prevention of corneal graft rejection

The management of an episode of corneal graft rejection (CGR) is primarily by corticosteroids. Immunomodulators are useful for long-term immunosuppression and in dealing with cases of high-risk (HR) corneal grafts. The classical signs of CGR following penetrating keratoplasty (PKP) include rejection line, anterior chamber (AC) reaction, and graft edema. However, these signs may be absent or subtle in cases of endothelial keratoplasty (EK). Prevention of an episode of graft rejection is of utmost importance as it can reduce the need for donor cornea significantly. In our previous article (IJO_2866_22), we had discussed about the immunopathogenesis of CGR. In this review article, we aim to discuss the various clinical aspects and management of CGR.

"Groove and Peel" Deep Anterior Lamellar Keratoplasty: How Deep Can You Go?

PURPOSE

The aim of the current research was to measure the thickness of the residual central corneal bed after performing the manual "Groove and Peel" deep anterior lamellar keratoplasty (GP-DALK) technique on human cadaveric eyes.

METHODS

The manual GP-DALK technique was performed on 6 human cadaver eyes by an experienced corneal surgeon. After surgery, the eye globes were fixed in 10% buffered formalin and embedded in paraffin. For each eye, 4-μm-thick hematoxylin and eosin sections involving the pupillary axis were obtained and examined. Using an image-processing software, 2 observers measured the corneal thickness of the residual central corneal bed and the peripheral corneal rims.

RESULTS

The overall mean central corneal bed thickness was 35.5 ± 12.9 μm, whereas the mean right and left peripheral rim thicknesses were 993.0 ± 141.1 and 989.3 ± 147.1 μm, respectively ( P = 0.0006 ). In most corneas, the level of dissection reached almost to the pre-Descemetic collagen (Dua) layer.

CONCLUSIONS

The GP-DALK technique is effective in removing most of the corneal stroma and may be non-inferior to "big-bubble" deep anterior lamellar keratoplasty in some cases.

Comparison of Endothelial Cell Loss following the Big Bubble versus the Microbubble Incision Technique during Deep Anterior Lamellar Keratoplasty in Eyes with Keratoconus

Introduction. Deep anterior lamellar keratoplasty (DALK) is now becoming an increasingly popular surgical technique in treating corneal stromal pathologies with healthy endothelium. Several advantages of DALK over penetrating keratoplasty (PKP) have been described such as maintenance of globe integrity, absence of endothelial rejection, and a low rate of chronic endothelial cell loss (ECL). ECL following PKP results in 50% cell loss after 2 years from the estimated graft endothelial cell density (ECD). Although there are several reports confirming that ECL following DALK is similar to the physiologic cell loss 2 years after surgery, few reports discussed the surgically induced ECL due to difficulty in preoperative imaging of ECD. Materials and Methods. This prospective, interventional study included 20 eyes of 20 patients, who underwent DALK surgery. 11 eyes underwent DALK using the big bubble technique, while 9 eyes underwent the microbubble technique. Postoperative evaluation was done 3 months after surgery and included best spectacle corrected visual acuity (BSCVA), keratometric readings, and refraction measured using an autokeratorefractometer (Topcon KR800, Japan) and endothelial cell density (ECD) using noncontact specular microscopy (Nidek CEM-530, Japan). Results. Regarding postoperative parameters such as postoperative logMAR visual acuity, postoperative mean K, and postoperative K max, there was no statistical difference found between both groups ( $P=0.754$ , $P=0.119$ , and $P=0.970$ , respectively). Regarding change in specular endothelial cell density and percent change in the specular endothelial cell density, again there was no statistical difference between both groups with $P=0.057$ and $P=0.126$ , respectively (significance defined as $P<0.05$ ). Conclusion. ECD is not affected by failure of the big bubble to form and continuing DALK via the microbubble technique.

Approaches toward enhancing survival probability following deep anterior lamellar keratoplasty

The greatest advantage of deep anterior lamellar keratoplasty over full-thickness corneal transplantation is the elimination of graft failure caused by endothelial rejection. Despite this advantage, a deep anterior lamellar keratoplasty graft can fail because of several factors, such as complications related to the donor-recipient interface, graft epithelial abnormalities, graft vascularization, stromal graft rejection, and recurrence of herpetic keratitis. Increased deep anterior lamellar keratoplasty graft survival is mainly built upon optimization of the ocular surface to provide a hospitable environment for the graft. Any predisposing factors for graft epithelial abnormalities, corneal neovascularization, and preexisting vernal keratoconjunctivitis should be identified and treated preoperatively. Prompt recognition and appropriate treatment of interface-related complications and stromal graft rejection usually result in good anatomic outcomes, with no detrimental effects on vision.

Factors Affecting Formation of Type-1 and Type-2 Big Bubble during Deep Anterior Lamellar Keratoplasty

Purpose: To determine the factors associated with the formation of different types of big bubble (BB) during DALK. Methods: In this retrospective study, 322 consecutive eyes of 307 patients with corneal stromal disorders who underwent DALK between January 2014 and June 2017 were included. Age, sex, corneal pathology, visual acuity, corneal curvature, corneal thickness, and adverse events were recorded. The main outcome measure was the success of BB formation with respect to the corneal pathology. Results: Type-1 BB was achieved in 147 eyes (45.7%), whereas type-2 BB was formed in 109 eyes (33.9%). The overall success rate of BB formation was 82.9%. Type-1 BB formation in keratoconus patients was significantly higher than type-2 BB (83.8% vs 2.6%, p < 0.001). In contrast, type-2 BB formation was significantly higher than type-1 BB (61.0% vs 15.6%, p < 0.001) in patients with corneal scars. Type-1 BB was more likely to be seen in patients with superficial corneal scarring, granular, and lattice dystrophies, while corneas with deep scarring and macular dystrophy had more type-2 BB. The type of bubble was not associated with age and gender of the patients. Conclusions: The overall success of big-bubble (BB) deep anterior lamellar keratoplasty (DALK) depends on the preoperative corneal pathology. Type -1 BB was more commonly seen in keratoconus patients whereas type-2 BB was observed in patients with deep corneal scars and other corneal pathologies affecting deeper layers of corneal stroma.

Prediction of Descemet Membrane Perforation During Deep Anterior Lamellar Keratoplasty in Patients With Keratoconus With Stromal Scar

OBJECTIVES

To report big-bubble deep anterior lamellar keratoplasty (DALK) in patients with keratoconus with corneal stromal scar, and to investigate factors that can influence intraoperative Descemet membrane (DM) perforation.

METHODS

A retrospective study included patients with keratoconus with central stromal scar that underwent DALK using the big-bubble technique. Best spectacle-corrected visual acuity (BSCVA), keratometry, minimum corneal thickness (MCT), stromal scar depth, and endothelial cell density (ECD) were recorded. Receiver operating characteristic (ROC) curves were analyzed to predict an intraoperative perforation related to stromal scar.

RESULTS

Thirty-eight eyes of 38 patients with keratoconus (mean age: 30.0±9.2 years) were included in this study. Thirty-four eyes had successful DALK; in four eyes, the procedure was converted to penetrating keratoplasty because of DM macroperforations. Successful big-bubble formation was achieved in 24 of 38 (63.2%) eyes, whereas in 10 eyes, manual dissection was used to complete the DALK. Mean preoperative and postoperative second year BSCVA were 1.3 (±0.4) and 0.5 (±0.2) logarithm of the minimum angle of resolution (P<0.001), keratometry values were 65.5±7.4 and 42.8±7.8 diopters (P<0.001), and ECD were 2,740±359 and 2,279±452 cells/mm (P<0.001), respectively. Using ROC analysis, the area under curve value to predict DM perforation was found to be 0.792 (scar/MCT ratio, P=0.04) and the best cutoff point for scar depth/MCT ratio was 53%.

CONCLUSION

Big-bubble DALK is effective in patients with keratoconus with stromal scars. Scar depth/MCT ratio seems to predict the DM perforation.

Immunologic Stromal Rejection After Deep Anterior Lamellar Keratoplasty With Grafts of a Larger Size (9 mm) for Various Stromal Diseases

PURPOSE

To evaluate the rate and outcomes of immunologic stromal rejection occurring after large deep anterior lamellar keratoplasty (DALK) and the effect of the underlying disease on the cumulative probability of rejection.

METHODS

This was a retrospective chart review of all eyes that underwent a 9-mm DALK at Ospedali Privati Forlì (Forlì, Italy). On the basis of preoperative diagnosis, eyes were assigned to group 1: keratoconus, group 2: stromal disease with a low risk for rejection, or group 3: stromal disease with a high risk for rejection. The cumulative probability of experiencing a rejection episode over time was assessed by Kaplan-Meier analysis and was compared among the 3 groups using the log-rank test. Values of corrected distance visual acuity, central corneal thickness, and endothelial cell density before and 6 months after rejection were compared.

RESULTS

Twenty of 377 eyes (5.3%) experienced an episode of stromal rejection [17/265 (6.4%) in group 1, 2/71 (2.8%) in group 2, and 1/41 (2.4%) in group 3]. The mean time interval between DALK and the rejection onset was 11.8 months (range 1-24). The cumulative probability of rejection episodes did not differ significantly among the 3 groups. All episodes resolved within 6 months after the onset, with no significant differences between prerejection and 6-month postrejection values of corrected distance visual acuity, central corneal thickness, and endothelial cell density.

CONCLUSIONS

The rate of immunologic stromal rejection after large 9-mm DALK is within the range reported in the literature for conventional DALK, regardless of the indication for surgery.

Microbubble technique in failed deep anterior lamellar keratoplasty: 2-year outcomes

Purpose:

To compare the long-term results of big-bubble technique and microbubble techniques to complete stroma dissection after failure of achieving a big-bubble.

Methods:

A total of 35 eyes with keratoconus underwent lamellar keratoplasty with the big-bubble technique (15 eyes) or the microbubble technique (15 eyes). Conversion to penetrating keratoplasty was performed in 3 eyes of the big-bubble group and in 2 eyes of the microbubble group. Best-corrected visual acuity, corneal thickness, corneal astigmatism, and endothelial cell count were assessed preoperatively and at 12 and 24 months after surgery.

Results:

Mean preoperative visual acuity was 0.29 ± 0.18 in the big-bubble group and 0.25 ± 0.15 in the microbubble group. Postoperatively, all patients showed a regular interface between donor and recipient tissue. At 24 months, mean best-corrected visual acuity was 0.84 ± 0.16 in the big-bubble group and 0.68 ± 0.17 in the microbubble group (p = 0.013), and mean central corneal thickness was 530 ± 39 µm in the big-bubble group and 545 ± 30 µm in the microbubble group. Astigmatism was 2.41 ± 1.29 D and 3.59 ± 1.48 D (p = 0.036), respectively, while endothelial cell density was 1,671 ± 371 in the big-bubble group and 1,567 ± 275 in the microbubble group.

Conclusions:

The microbubble technique appears to be a valid alternative as it was safe and provided good functional results.

Salvaging deep anterior lamellar keratoplasty with microbubble incision technique in failed "big bubble" cases: an update study

PURPOSE

To report the achievement rate of bare Descemet membrane (DM) dissection with the help of microbubble incision technique in eyes with failed big bubble formation and to investigate the mechanism of the microbubble rescue technique through ex vivo imaging of human cadaver corneas.

METHODS

This retrospective clinical study included 80 eyes of 80 patients that underwent deep anterior lamellar keratoplasty (DALK). In 22/80 (27.5%) cases, big bubble dissection failed. After puncturing the microbubbles, viscodissection helped to achieve separation of DM from the remaining stroma. In addition, an ex vivo study with human cadaver cornea specimens, gross photography, and anterior segment optical coherence tomography imaging was accomplished ex vivo to explore the mechanism of this method.

RESULTS

Microbubble dissection technique led to successful DALK in 19 of 22 cases of failed big bubble. Microperforation occurred in 3 eyes. Deep anterior lamellar keratoplasty was completed without any complications in 2 out of the 3 eyes with microperforation. In 1 eye, conversion to penetrating keratoplasty was required. Microbubble-guided viscodissection achieved 95.4% (21/22) success in exposing bare DM in failed big-bubble cases of DALK. Anterior segment optical coherence tomography imaging results of cadaver eyes showed where these microbubbles were concentrated and their related size.

CONCLUSIONS

Microbubble-guided DALK should be considered an effective rescue technique in achieving bare DM in eyes with failed big bubble. Our ex vivo experiment illustrated the possible alterations in cornea anatomy during this technique.

Outcomes of Air Injection Within 2 mm Inside a Deep Trephination for Deep Anterior Lamellar Keratoplasty in Eyes With Keratoconus

PURPOSE

To evaluate the outcomes of a new technique for deep anterior lamellar keratoplasty (DALK) employing the injection of air up to 2 mm inside a deep trephination (intended within 100 μm from the endothelial surface) obtained with a guarded trephine set by means of anterior segment optical coherence tomography (AS OCT).

DESIGN

Retrospective, noncomparative, interventional case series.

METHODS

The success rate and learning curve of pneumatic dissection in one clinical practice were analyzed in nonscarred keratoconic eyes undergoing a standardized DALK including 9-mm trephination intended to a depth within 100 μm from the endothelial surface, based on the thinnest AS OCT measurement at this site; and injection of air through a cannula advanced 1-2 mm centripetally from the bottom of the trephination. Surgical parameters, success rate of pneumatic dissection, and complications were recorded.

RESULTS

Eighty-eight eyes of 88 patients were included in the study. Pneumatic dissection succeeded in 75 of 88 eyes (85%). No significant correlation could be found between number of cases performed and success rate for this surgeon. Complications included loss of suction during trephination (n = 2, 2.3%) and perforation (n = 4, 4.6%). Conversion to penetrating keratoplasty was necessary in 1 case (1.1%).

CONCLUSION

Setting an adjustable trephine to a depth within 100 μm from the endothelial surface eliminates the need for reaching the central cornea for successful pneumatic dissection and substantially flattens the learning curve of DALK, while achieving a constant success rate above 80% and minimizing complications.

Morphometric changes of corneal endothelial cells following intracameral air for micro perforation of the Descemet Membrane during big-bubble deep anterior lamellar keratoplasty

Aim

The aim of this study was to assess the effect of intracameral air on the endothelial cell morphometrics.

Patients and methods

This is a retrospective controlled interventional cohort study of 26 patients (18 males and 8 females) who underwent unilateral deep anterior lamellar keratoplasty (DALK) for moderate keratoconus. The DALK patients were divided into two groups: a treatment group (14), which had micro perforations of the Descemet Membrane (DM) intraoperatively and received intracameral air at the end of the surgery; and an independent control group (12), which had no micro perforation and thus no intracameral air was injected. Postoperative best corrected visual acuity (BCVA), sphere, cylinder, spherical equivalent (SEQ), central corneal thickness, and endothelial cell morphometric features consisted of the endothelial cell density (ECD), polymegathism, and pleomorphism were compared between treatment and control groups.

Results

The mean BCVA was 0.36 ± 0.36 logMAR in the treatment group and 0.17 ± 0.11 logMAR in the control group (p = 0.081), and the mean corneal thickness was 507.86 ± 62.69 μm in the treatment group and 525.67 ± 37.54 μm in the control group air (p = 0.399). Furthermore, the mean sphere was −5.14 ± 4.17D and −1.02 ± 3.29D, the mean cylinder was −3.16 ± 2.20D and −2.88 ± 1.21D, and the mean SEQ was −6.72 ± 4.66D and −2.46 ± 3.14D and in the treatment and control groups respectively (p = 0.011, 0.693, and 0.013). As to morphometric features, the mean ECD was 2176.76 ± 549.18 cell/mm² and 2257.30 ± 436.12 cell/mm² in the treatment and control groups respectively (p = 0.686), and the mean pleomorphism 0.48 ± 0.09 and 0.54 ± 0.10 in the treatment and control groups respectively (p = 0.139). In contrast, the mean polymegathism was 0.37 ± 0.06 and 0.31 ± 0.05 in the treatment and control groups respectively (p = 0.009).

Conclusion

The presence of air inside the anterior chamber for a short term may not cause further endothelial cell loss and can be safely performed to prevent postoperative Descemet Membrane detachment in case of micro perforations.

Trends in corneal transplantation: indications and techniques

PURPOSE OF REVIEW

To describe trends in corneal transplantation surgery, including indications for surgery, evolution of lamellar keratoplasty, current surgical techniques, and future directions.

RECENT FINDINGS

Over the past decade, anterior and posterior lamellar keratoplasty have begun to supplant penetrating keratoplasty. Surgical techniques continue to change and improve outcomes. In recent years, Descemet membrane endothelial keratoplasty (DMEK) has gained interest as it eliminates the corneal stromal interface, which may limit visual acuity after Descemet stripping automated endothelial keratoplasty. Despite the promising results with improved visual acuity and decreased rejection, the technical challenges associated with DMEK have limited widespread acceptance. With technical refinements and more eye banks providing precut tissue for both Descemet stripping automated endothelial keratoplasty and DMEK, it is likely both procedures will continue to increase over time.

SUMMARY

Corneal transplantation has evolved rapidly over the past decade, from full-thickness penetrating keratoplasty towards lamellar keratoplasty to only remove and replace damaged layers of the cornea. Achieving minimal induced astigmatism with excellent visual acuity remains a challenge in corneal transplantation. Further refinements in surgical technique may help improve technical challenges and visual outcomes. In this article, we review changing trends in corneal transplantation and highlight developing medical treatments that may be available in the future.

Big bubble deep anterior lamellar keratoplasty for management of deep fungal keratitis

Objective. To evaluate the therapeutic effect of big bubble deep anterior lamellar keratoplasty (DALK) in patients with deep fungal keratitis. Methods.Consecutive patients who had DALK for deep fungal keratitis at Shandong Eye Hospital between July 2011 and December 2012 were included. In all patients, the infiltration depth was more than 4/5ths of the corneal thickness. DALK surgery was performed with bare Descemet membrane (DM) using the big bubble technique. Corrected distance visual acuity (CDVA), graft status, and intraoperative and postoperative complications were monitored. Results. Big bubble DALK was performed in 23 patients (23 eyes). Intraoperative perforation of the DM occurred in two eyes (8.7%) during stromal dissection. The patients received lamellar keratoplasty with an air bubble injected into the anterior chamber. Double anterior chamber formed in 3 eyes (13.0%). Mean CDVA of the patients without cataract, amblyopia, and fungal recurrence was improved from preoperative HM/20 cm−1.0 (LogMAR) to 0.23 ± 0.13 (LogMAR) at the last followup (P < 0.01). Fungal recurrence was found in two patients (8.7%). Corneal stromal graft rejection was noted in one patient (4.3%). Conclusions. DALK using the big bubble technique seems to be effective and safe in the treatment of deep fungal keratitis unresponsive to medication.

New perspectives on lamellar keratoplasty

Lamellar (anterior and posterior) keratoplasty entails the surgical replacement of diseased-only corneal tissue, while healthy host corneal tissue is preserved. Selective keratoplasty offers several advantages in comparison to penetrating keratoplasty such as a lower rate of graft rejection, less endothelial cell loss, faster/superior visual rehabilitation and enhanced resistance to closed injury. The surgical approach of "partial corneal transplantation" may be divided into anterior and posterior: techniques including superficial and deep anterior lamellar keratoplasty (SALK and DALK, respectively) and endothelial keratoplasty as well as Descemet stripping automated endothelial keratoplasty (DSAEK) and Descemet membrane endothelial keratoplasty (DMEK). These novel surgical procedures are rapidly becoming the preferred therapy option for specific corneal dysfunctions involving the corneal stroma (SALK, DALK), or corneal endothelium (DSAEK, DMEK). During the past decade, the continuing advancement of surgical techniques and the development of innovative surgical instruments have significantly enhanced corneal transplantation. Lamellar keratoplasty techniques facilitate corneal surgery, provide patients with superior outcomes and can successfully restore vision in corneal-related blindness. Nevertheless, more long-term evidence is needed to better evaluate these promising new techniques.

Deep anterior lamellar keratoplasty versus penetrating keratoplasty for macular corneal dystrophy: a randomized trial

PURPOSE

To compare outcomes of big-bubble deep anterior lamellar keratoplasty (DALK) and penetrating keratoplasty (PK) for macular corneal dystrophy.

DESIGN

Prospective, randomized, interventional case series.

METHODS

setting: Single hospital. patients: Eighty-two eyes of 54 patients requiring keratoplasty for the treatment of macular corneal dystrophy without endothelial involvement were included. main outcome measures: Operative complications, uncorrected visual acuity, best-corrected visual acuity, contrast sensitivity function, higher-order aberrations, and endothelial cell density were evaluated.

RESULTS

The DALK and PK group consisted of 35 and 41 eyes, respectively. Best-corrected visual acuity after surgery was 20/40 or better 68.5% and 70.7% of the eyes in the DALK and PK groups, respectively (P > .05). No statistically significant differences between groups were found in contrast sensitivity function with and without glare for any spatial frequency (P > .05). Significantly higher levels of higher-order aberrations were found in the DALK group (P < .01). In both groups, a progressive and statistically significant reduction in endothelial cell density was found (P < .01). At the last follow-up, the mean endothelial cell loss was 18.1% and 26.9% in DALK and PK groups, respectively (P = .03). Graft rejection episodes were seen in 5 eyes (12.1%) in the PK group, and regrafting was necessary in 3 eyes (7.3%). Recurrence of the disease was documented in 5.7% and 4.8% of the eyes in the DALK and PK groups, respectively.

CONCLUSIONS

Deep anterior lamellar keratoplasty with the big-bubble technique provided comparable visual and optical results as PK and resulted in less endothelial damage, as well as eliminating endothelial rejection in macular corneal dystrophy. Deep anterior lamellar keratoplasty surgery is a viable option for macular corneal dystrophy without endothelial involvement.

Deep anterior lamellar keratoplasty for the treatment of stromal corneal dystrophies

PURPOSE

To report the perioperative complications and clinical outcomes after deep anterior lamellar keratoplasty (DALK) using the big bubble technique in eyes with stromal corneal dystrophies.

PATIENTS AND METHODS

Seventy-four eyes of 65 patients who underwent DALK for stromal corneal dystrophies were evaluated in this retrospective interventional case series study. Main outcome measures were intraoperative and postoperative complications, postoperative uncorrected visual acuity, best spectacle-corrected visual acuity, spherical equivalent refraction, and topographic astigmatism.

RESULTS

There were 44 eyes with macular corneal dystrophy, 18 eyes with lattice dystrophy, and 12 eyes with granular dystrophy. DALK was completed in 69 cases (94.6%). Descemet membrane microperforations occurred in 6 eyes (8.7%). The mean follow-up period was 43.5 ± 23.9 months, ranging from 12 to 96 months. Postoperative best spectacle-corrected visual acuity of 0.5 or better was present in 52 of 69 eyes (75.4%). There were 3 episodes of stromal graft rejection, which responded to topical therapy. Lattice dystrophy recurred in 6 eyes (35.3%).

CONCLUSION

DALK using the big bubble technique is an effective procedure in the treatment of patients with corneal stromal dystrophies. Recurrence of lattice dystrophy was relatively high.

Microbubble incision as a new rescue technique for big-bubble deep anterior lamellar keratoplasty with failed bubble formation

PURPOSE

To describe a new surgical technique allowing dissection down to Descemet membrane in big-bubble deep anterior lamellar keratoplasty (DALK) with failed big-bubble formation (the "microbubble incision technique").

METHODS

This is an interventional case series of 10 consecutive patients with keratoconus undergoing intended big-bubble DALK with failure to establish a normal big bubble. In all patients, repeated air injections into the stroma were performed, leaving a whitish colored stroma. Lamellar dissection as far down as possible was then performed within this white tissue. As soon as the anterior chamber was visible, a large remaining intrastromal air bubble was incised with a sharp 15-degree knife introduced perpendicular to the tissue to open up this predescemetic bubble. If deeper air bubbles were still visible, this approach was repeated. Using a blunt spatula, this new layer was then prepared and viscodissection performed.

RESULTS

Using this novel approach, in 9 of the 10 patients, it was possible to dissect down to Descemet membrane. Macroperforation made conversion to penetrating keratoplasty necessary in 1 patient. Microperforations not necessitating conversion occurred in 2 patients. All 9 patients with "rescued" DALK had an uneventful postoperative course and had a mean visual acuity of 20/63 ± 20/125 (range, 20/500-20/50) and a mean endothelial cell count of 1672 ± 163 cells per square millimeter (range, 1493-1867 cells/mm) at 3 months.

CONCLUSIONS

Microbubble incision is a new rescue technique for big-bubble DALK patients without bubble formation allowing for a safer dissection down to Descemet membrane.

Therapeutic effect of deep anterior lamellar keratoplasty for active or quiescent herpetic stromal keratitis

PURPOSE

To evaluate the therapeutic effect of deep anterior lamellar keratoplasty (DALK) in patients with herpetic stromal keratitis (HSK).

METHODS

Forty-three eyes belonging to 42 patients with HSK, including 22 eyes in the active phase and 21 eyes in the quiescent phase, underwent DALK at the Shandong Eye Institute from January 2006 to December 2009. All patients with active disease had received intravenous acyclovir and amniotic membrane implants prior to DALK. Herpes simplex virus type 1 (HSV-1) antigens from excised corneal buttons were detected by immunohistochemistry.

RESULTS

The follow-up ranged from 1 to 4 years (mean, 29.1 months). Graft rejection occurred in one eye (2.3%) and was reversed. Among the other 42 survived grafts (97.7%), 37 remained clear at the last visit. The best spectacle-corrected visual acuity was 20/200 or better in 95.2% of eyes and 20/40 or better in 38.1% of eyes. Six eyes (14.0%) developed recurrent HSK, one of which received a second keratoplasty due to ineffective antiviral medication. There were no significant differences in endothelial cell density between 6 months and 12 months after the surgery. By immunohistochemistry, HSV-1 antigens were observed in the stroma of 18 of 32 corneal buttons.

CONCLUSIONS

DALK can not only remove the corneal lesions of HSK but also reduce latent or persistent viral loads in the cornea. In eyes with active or quiescent HSK but otherwise healthy endothelia, DALK seems to be safe and promising for its favorable visual outcome, graft survival rate, and low endothelial cell loss.

Long-term results of deep anterior lamellar versus penetrating keratoplasty

OBJECTIVE

To compare deep anterior lamellar keratoplasty (DALK) with penetrating keratoplasty (PK) in eyes with corneal diseases not involving the corneal endothelium (keratoconus, scars after infectious keratitis, stromal dystrophies, and trauma).

DESIGN

Retrospective, comparative case series.

PARTICIPANTS

One hundred forty-two consecutive DALK (DALK group; big-bubble technique or manual lamellar dissection using a slitlamp) and 142 matched PK (PK group).

METHODS

Three models were used to describe the postoperative outcomes of the endothelial cell density. A joint regression model was used to predict long-term graft survival. Visual acuity, ultrasound pachymetry, specular microscopy, and optical coherence tomography (OCT) findings were recorded.

MAIN OUTCOME MEASURES

Postoperative endothelial cell loss and long-term predicted graft survival.

RESULTS

The average 5-year postoperative endothelial cell loss was -22.3% in the DALK group and -50.1% in the PK group (P<0.0001). The early- and late-phase annual rates of endothelial cell loss were -8.3% and -3.9% per year, respectively, in the DALK group and -15.2% and -7.8% per year in the PK group (P<0.001; biphasic linear model). The median predicted graft survival was 49.0 years in the DALK group and 17.3 years in the PK group (P<0.0001). The average visual acuity was lower in the manual dissection subgroup compared with the PK group (average difference, 1.0 to 1.8 line) and with the big-bubble subgroup (average difference, 2.2 to 2.5 lines). The average central corneal thickness at 12 months was 536 μm in the PK group, 523 μm in the big-bubble subgroup, and 562 μm in the manual dissection subgroup (P<0.001). The average thickness of the residual recipient stroma measured by OCT was 87±26 μm in the manual dissection subgroup. No correlation was found between this figure and logarithm of the minimal angle of resolution at any postoperative time point (P>0.05).

CONCLUSIONS

Long-term, model-predicted graft survival and endothelial densities are higher after DALK than after PK. The big-bubble technique gives better results than manual dissection and PK. Compared with PK, manual dissection provides higher survival of both the corneal endothelium and graft, but lower visual acuity.